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This is the hydraulic pump for a mower conditioner. It runs off the PTO. Somebody out there might have one, and be interested in the repair.
The input shaft seal (where the pump attaches to the PTO) has started leaking, and it's not wise to run it in this shape. Small leaks can become big leaks faster than you can blink an eye.Drain any residual oil from the gearbox.
The seal, and bearing, are in the front cover. Remove the bolts, and sit the assembly on something CLEAN.
The entire assembly comes off with gentle tapping using a rubber hammer.Next, remove the snap ring that holds the cover on the the bearing.
The cover assembly is then gently tapped off of the bearing, which remains attached to the shaft.
Reply:The shaft has some serious issues.
It's badly rusted where the seal rides. This is due to sitting in the mud between seasons. I need to build a cradle for the doggone thing to keep it off the ground. The machine has provision for storing the pump assembly, but it puts a huge strain on the hoses, which can lead them to take a "set", and later go bad where the stress occurred. If the rust can't be removed with steel wool, it'll be dressed with 180 grit emery cloth. The idea is to remove as little material as possible from the shaft. Just enough to get rid of the rust without scoring the metal. Total PITA. I have no idea whether the bearing is a press fit......but if it is......it will remain on the shaft during the dressing procedure with coverings to prevent any abrasive/rust/dirt from entering the bearing assembly. Total PITA.
Reply:Seen a lot of those pump drives on various pieces of farm equipment, mainly hydraulic PTO Freeman balers, I just clean the rust off down to steel and use a stainless "speedi-sleeve". Never have another issue with rust. Oh, those "no name" OEM seals are junk. get a good C/R or National to replace it.
Reply:
Originally Posted by 12V71
Seen a lot of those pump drives on various pieces of farm equipment, mainly hydraulic PTO Freeman balers, I just clean the rust off down to steel and use a stainless "speedi-sleeve". Never have another issue with rust. Oh, those "no name" OEM seals are junk. get a good C/R or National to replace it.
Reply:I believe I may have dodged the bullet on this one (whew)Steel wool didn't make a dent
Taped off the bearing to keep crud out, and headed into the Uranus Master Machine Shop to snag some ScotchBrite (well, it ain't REALLY ScotchBrite, it's some knockoff stuff).
I believe I'm good. It passes the fingernail test. No appreciable ridges, or transition points.
These are 2 lip seals. The inner lip keeps the oil in, and the outer seal keeps the dirt out. Most of the rust damage was between the inner and outer lip. It's a good bet that there's enough smooth shaft remaining for the seal to ride on. The polishing eased any damaged areas into the good areas. So, it's hope for the best.BTW...............The correct sleeve for this shaft would be a National # 99210 Repair Sleeve ($45). At least I know it's available if need be.
Reply:While waiting for the new seal, it's time to make a seal driver.A blank is cut to size with the torch, then rough gound. This is a piece of scrap leftover from something else. The hole had been machined prior for a die that I decided was the wrong radius.The bore is measured, and the narrow end marked so it can be smoogied to take the taper out. About 2 thousands taper. An annular cutter will leave a taper.
Die grinder with a mounted stone, and the taper disappears.......then the final finish diameter is marked on the piece. I prefer to mark something rather than trust it to memory.
This is to be a shrink fit. One part heated, and the "cold' part dropped into the hole. The shaft is turned to the appropriate interference fit.
I used an indexable carbide tool to turn the shaft. The final .015 was taken in a single cut........no sneaking up on it. Carbide isn't good at sneaking up on a dimension........better to go for broke, and set your machine to the finish tolerance. It turned out ok.I like to cut a bit of a relief on the shaft when doing a shrink fit, or press fit. This prevents the shoulder from interfering with the shoulder on the other part it fits into. For something really SpaceX, I'da used a cutoff blade to make the relief........in this case I just notched it with the carbide cutter. Not as elegant, but does the trick.
Reply:Put the heat to the donut, and drop the shaft in.
Cutting the relief made for a nice flush fit.
Pop it in the lathe tomorrow, and turn the thing to size.
Reply:Not saying either of us are right or wrong, but this is how I build seal drivers. The big one is made from 1" threaded rod and a chunk of 1" pipe. Got a huge collection of different plates up to 11". I use my circle cutter for the torch to make 'em and then bore the hole. There are a few that I have had to use a lathe to get really precise or put special grooves in. Most are fine with a good torch setup and a bit of grinding.
Reply:In my crappy little world, it's never that easy
The seal is recessed in the bore
Which is just shy of .500 deep.
And naturally
the seal is 3/8 thick
In the bad old days, I'd find a socket that was near enough in size to fit the seal, or use a small drift to seat the seal once it's tapped in flush. Or, I'd use the old seal for the final seating, then pry it out of the bore. Which in about 1/2 the cases........wound up messing up the seal cup. Thank God I have the lathe. I can turn something for a nice sliding fit inside the bore, and not worry about messing up the seal cup. PITAI feel I'll soon be replacing the identical seal on the other mower (1010 Hydroswing) soon, so I'll at least have something made for that job too.
Reply:The seals came in, and I got the seal driver finished today.Find the diameter of the bore..........
Turn the rough blank using a sacrificial bit. I really like HSS for this kind of thing. You might ding the tip a bit, but it's a quick fix on the grinder if it's bad, or a quickie touch up with a stone if it's not. Carbide really doesn't like this kinda stuff.The workpiece was moved out a bit so the edges could be eased with a file, and the surface polished.
If you're not familiar with them..........lathe files are very handy. They're strictly directional cut, and make it very easy to ease an edge without resorting to changing your toolpost position. In this case, I wanted a nice rounded leading edge....the file is perfect for this.
Reply:Nice slip fit in the bore.........I allowed .010
I put, what is for me, a fairly high polish on the O.D. The casting is aluminum, and tends to be gummy, and hang tools up. Slicker tool,, less chance of galling the bore.
Put 'er all together tomorrow morning, and move on I guess.
Reply:Before I forget.........I used the Uranus 469 Shear Bit to get to the final dimension. I love this thing for mild steel. Fast, smooth, and no gummy tearing.
Reply:Installed two seals today
One the wrong way, and one the right way
Popped the first one in, and looked at it. Didn't seem evenly seated in the bore.................I'm using an arbor press for the work because it's more sensitive to applied pressure. You can feel the moment something bottoms, and don't run the danger of over stressing the part.
Couldn't immediately figure out what was wrong. Then it hit me
The seal seats against a ring at the bottom of the bore, which is in a groove in the bore itself.
The ring is made of spring steel, and is fairly loose in the groove (isn't thick enough to fully fill the groove width)........allowing crud to build up in the groove.
The ring can be removed by prying the tab on the end of the coil.
A good quality, not that import crap, dental pick can be used to pry the end out, then a screwdriver is inserted to pry it out further...........then you simply coil it out of the groove.
Reply:Dirt, and rust, had fouled the groove, and worked its way into the ring coil. So, naturally the seal couldn't accurately bottom where it's supposed to be. Cleaned it all up, and finished out the job. Good to go.
Checked the seating depth with a depth micrometer, and I'm about .005 out on one side. I can live with that. The ring doesn't provide a really good square seating surface. I suppose they didn't machine a land because the seal seats so close to the outside nose of the casting. I'm thinking that the aluminum isn't strong enough for the possible pressure used to seat the seal, or some other reason associated with material strength. Whatever the reason...........it's something to be aware of. Can't assemble these without thoroughly cleaning the groove, and ring. |
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发表于 2021-9-1 23:14:43